Cosmetic composition with skin tightening effect

ABSTRACT

The present invention relates to a mixture, having a skin-tightening effect, which is made up of:
         10 to 80% by weight of a polysaccharide, preferably of an alginate, having a molecular weight of less than 600,000 Daltons, preferably less than 400,000 Daltons and more preferably less than 200,000 Daltons,   15 to 75% by weight of a polyhydroxylated agent selected from sugars and their derivatives, particularly sugar esters and sugar, ethers, preferably sorbitol,   3 to 15% by weight of poly(vinyl alcohol) or polyvinylpyrrolidone, and   0 to 25% by weight of cellulose or of a derivative of cellulose, such as carboxymethylcellulose or hydroxymethylcellulose.       

     The present invention also relates to cosmetic compositions which contain this mixture. 
     These cosmetic compositions enable a mechanical smoothing of the surface of the skin to be obtained progressively with great comfort of use and enables a good fixing of make-up products.

This is a Continuation Application of U.S. patent application Ser. No.10/487,693, filed Feb. 26, 2004, which was filed under 35 U.S.C. 371 asa national stage of PCT/FR02/02941, filed Aug. 27, 2002, and claimsbenefit to French Priority Application No. 0111123, filed on Aug. 27,2001, the entire content of each of which is hereby incorporated byreference in its entirety.

The invention relates essentially to a mixture having a tighteningeffect on the surface of the skin, as well as to its use for preparing acosmetic composition having a tightening effect for smoothing thesurface of the skin.

It is known from the document FR-A-2,478,468 of a composition whichcomprises a mixture of two fractions of hyaluronate of differentmolecular weight, one having a low molecular weight of the order of10,000 to 200,000 Daltons and the other of high molecular weight of theorder of 1,000,000 to 4,500,000 Daltons, in a determined weight ratio ofbetween 0.3 and 2, a protein originating from the natural substancebeing used as source of hyaluronate, as well as water as the remainder.

This composition can also contain 0.05 to 5% of sugar-alcohol such assorbitol, as well as 0.2% to 1% of polysaccharide such as an alginate.This document does not disclose in any way the use of products having atightening effect in the sense of the present invention. It emerges fromthe description of this patent application that the composition isdescribed essentially as having a moisturising effect.

It is also known from the document WO 96/19180 of the use, in acomposition notably for toning up the skin, of polysaccharides combinedwith caseine. Said polysaccharides are used at low concentration as afilmogenic agent. This document does not disclose in any way that thecomposition described possesses any effect of mechanical smoothing ofthe surface of the skin.

Japanese patent application JP 60 55048 describes cosmetic compositionswhich contain, as essential constituents, 25 to 80% by weight of sodiumalginate and 15 to 70% of polyhydric alcohol. These compositions possessa good quality of adhesion to the skin and of moisturisation of it.

It has now been established, during tests carried out by the inventorsof the present invention with the view to developing a product having atightening effect on the surface of the skin, that surprisingly, theintroduction of poly(vinyl alcohol) or polyvinylpyrrolidone in mixturescontaining a polysaccharide and a sugar or a sugar derivative enabledthe properties of adhesion to the skin to be greatly improved and thatbesides, the addition of cellulose or of a derivative of cellulose tothis mixture comprising the three constituents (polysaccharide, sugar orsugar derivative and poly(vinyl alcohol) and/or polyvinylpyrrolidone),enabled any sensation of pulling of the skin to be avoided, inconferring elasticity to the polymeric matrix which is formed afterapplication of the composition on the skin, without causing looseningfor all that.

This led the inventors of the present invention to define novel mixturesof products which possess remarkable cosmetic properties and whichenable properties of a tightening effect on the skin, and of adhesion tothe skin, to be conferred to cosmetic compositions in which they areincorporated, which properties have not been hitherto observed and whichare linked to the simultaneous presence in the mixture of apolysaccharide, of a sugar or a sugar derivative and of poly(vinylalcohol) or polyvinylpyrrolidone and, eventually, of cellulose or ofcellulose derivatives, in well-defined proportions.

It emerges from the documentary study made by the inventors of thepresent invention that even if various documents of the literatureenvisage the presence of some of these constituents, even their whole incombination, none reveals or suggests the particular proportions ofthese constituents for obtaining a remarkable tightening effect obtainedaccording to the present invention.

Thus, Japanese patent JP-2053707 describes cosmetic compositions whichform a very thin film on the skin intended to reduce wrinkles and tonourish the skin. The compositions described in this documentessentially contain 0.2% of poly(vinyl alcohol), 2% ofhydroxymethylcellulose, 0.5% of sodium alginate, 5% of modified alcohol,4.96% of moisturising agent and 87.34% of water. This document does nottherefore suggest the introduction of a sugar.

Russian patent RU-2069557 describes a moisturising and cleansing creamwhich contains, amongst other constituents, methylcellulose, or sodiumalginate and glycerine.

This composition does not possess any tightening effect of the skin, norany effect of mechanical smoothing of wrinkles.

The patent JP-5207934 describes a cosmetic composition having a reducedcontent of poly(vinyl alcohol) nourishing the skin. This compositioncontains alginate as thickening agent at contents which do not enablethe tightening effect sought after according to the present invention,to be obtained.

Japanese application JP-5032523 describes cosmetic compositions whichcontain a hydrosoluble polymer which can contain, inter alia, cellulose,or sodium alginate, as well as optionally poly(vinyl alcohol). Thisproduct is described as having an oil-absorbent effect and as providinga sensation of freshness, and has no tightening effect on the skin.

The Korean application, published under the number KR-2001089938 waspublished on Oct. 17, 2001 and describes cosmetic compositions intendedto moisturise and to whiten the skin. These compositions contain 3.4% ofpoly(vinyl alcohol), 16.6% of sorbitol, 4.7% of glycerine, 30.2% ofzeolite, 3.6% of talc, 0.14% of chitosan, 0.26% of sodium alginate and41.1% of natural plant extracts in alcohol. The very low concentrationsof polysaccharide of the compositions described in this document do notenable in any way the tightening effect sought after according to thepresent invention; to be obtained.

The present invention enables a novel mixture, having a tighteningeffect on the surface of the skin, to be obtained for the preparation ofa cosmetic composition having a tightening effect in a controlledmanner, and enabling a visible and lasting smoothing of the surface ofthe skin with a great comfort of use.

The present invention also relates to solving the novel technicalproblem consisting of providing a novel product, notably having atightening effect on the surface of the skin, capable of actingeffectively in order to give a smoothing of the surface of the skin innotably obtaining a total or partial erasure of wrinkles, includingmedium and deep wrinkles.

The present invention enables this novel technical problem to be solvedfor the first time in a satisfactory, safe and reliable manner, whichcan be used on an industrial and cosmetic scale.

Thus, the invention relates, according to one of its essential features,to a mixture, having a skin-tightening effect, which is made up of:

-   -   10 to 80% by weight of a polysaccharide having a molecular        weight of less than 600,000 Daltons, preferably less than        400,000 Daltons and more preferably less than 200,000 Daltons,    -   15 to 75% by weight of a polyhydroxylated agent selected from        sugars and their derivatives, particularly sugar esters and        sugar ethers,    -   3 to 15% by weight of poly(vinyl alcohol) or        polyvinylpyrrolidone, and    -   0 to 25% by weight of cellulose or of a derivative of cellulose,        such as carboxymethylcellulose or hydroxymethylcellulose.

Advantageously, the above-mentioned polysaccharide is a pectin, acarrageenan, a galactomanane, a xanthan or an alginate.

According to a preferred embodiment, the polysaccharide is an alginate,particularly an alginate of propylene glycol, or an alginate in the formof an acid or a salt, particularly a sodium alginate.

Amongst the commercial alginates which can be used in the compositionsaccording to the present invention, those of Manugel type can be cited.

According to another particularly advantageous embodiment of theinvention, the above-mentioned polysaccharide is an alginate which is inthe form of an extract of alga, particularly an extract of alga of thefamily of Laminariacae, preferably an extract of Laminaria digitataalga, of Laminaria flexicaulis alga, or even of Laminaria saccharinaalga. Commercial extracts of algae do exist which are suitable for theimplementation of the invention. They are notably commercialised by thecompany 1 dB Holding, such as, for example: Laminaria digitata extract,Laminaria saccharina extract, Laminarine, or even Phytelene of LaminariaEG 483 liquid and EG 749.

According to an advantageous variant of the invention, the concentrationof polysaccharide is between 20 and 55% by weight with respect to thetotal weight of said mixture.

Advantageously, the polyhydroxylated agent is selected from sugars andtheir derivatives, particularly their esters or their ethers.

Preferably, the sugar is selected from C₆ sugars and C₁₂ sugars.

Advantageously, the C₆ sugar is selected from glucose, sorbitol,mannitol and galactitol, the C₁₂ sugar is selected from sucrose andlactitol.

According to an advantageous embodiment, the polyhydroxylated agent issorbitol.

According to a variant of the invention, the polyhydroxylated agent issorbitol and is in the form of a plant extract, particularly an extractof sorbs, such as a Sorbus aucuparia sorb extract, a Sorbus domesticasorb extract, or a Sorbus aria sorb extract.

According to another advantageous variant of the invention, theconcentration of polyhydroxylated agent is 40 and 65% by weight withrespect to the total weight of said mixture.

According to a particularly preferred embodiment of the invention, themixture, having a tightening effect on the surface of the skin, containsa Laminaria flexicaulis extract and an extract of sorbs, particularly anextract of Sorbus aucuparia.

According to a particularly advantageous embodiment of the invention,the concentration of polysaccharide is greater than the concentration ofpolyhydroxylated agent.

According to this embodiment, it was observed that the higherpolysaccharide concentration enables a matt appearance to be obtainedafter application of a composition containing said mixture having atightening effect.

According to another particularly advantageous embodiment of theinvention, the concentration of polyhydroxylated agent is greater thanthe concentration of polysaccharide. It was observed that when theconcentration of polyhydroxylated agent is greater than theconcentration of polysaccharide, a relatively shiny appearance isobtained after application of a composition which contains said mixturehaving a tightening effect.

According to yet another advantageous feature of this embodiment of theinvention, the concentration of poly(vinyl alcohol) (PVA) or ofpolyvinylpyrrolidone (PVP) is between 3 and 10% by weight with respectto the total weight of said mixture.

According to an advantageous feature, the mixture contains cellulose orone of its derivatives, preferably such as carboxymethylcellulose (CMC),and this at a concentration of between 1 and 8% by weight with respectto the total weight of said mixture.

It was noted that the PVA acts in synergy with the sugar, particularlywith the sorbitol, in order to procure a better adhesion to the skin ofthe cosmetic composition defined further on, and secondly that the PVAin the presence of CMC avoids the sensation of <<pulling>> of the skin,in conferring elasticity to the polymeric matrix which is formed afterapplication of said composition on the skin, without causing in all thata loosening.

The cosmetic composition defined further on, which is prepared from saidproduct, does in fact form a polymer matrix after application on theskin. The creep is defined as the property of the polymer matrix to takeshape under the action of a constraint. As for the loosening or therelaxation, it is defined as the property of the polymer matrix to losethe strength of tension when it undergoes a shaping. The term<<plastifying>> refers to qualities of softening and of elasticity ofthe polymer matrix.

Thus, it was noted that in changing the relative proportions of the fouressential constituents of the mixture of the invention, it was possibleto vary not only the tightening effect, but also to confer to thismixture an anti-creep action, an anti-loosening action and/or more orless marked plastifying action.

The preferred mixtures according to the invention are constituted ofalginate, of sorbitol, of PVA or of PVP and of CMC, in the followingproportions:

-   -   10 to 80%, preferably 20 to 55%, by weight of alginate,    -   15 to 75%, preferably 40 to 65%, by weight of sorbitol,    -   3 to 15%, preferably 3 to 10%, by weight of poly(vinyl alcohol)        or polyvinylpyrrolidone, and    -   0 to 25%, preferably 1 to 8%, by weight of        carboxymethylcellulose.

According to a second aspect, the invention relates to the use of theproduct having a tightening effect as defined above, for the preparationof a cosmetic composition having a tightening effect, with the view toobtaining a mechanical smoothing of the surface of the skin.

An intermediate mixture comprising 5 to 15%, preferably 8 to 10%, of themixture according to the invention, is in general prepared to this end,in a classical aqueous excipient.

More specifically, the invention relates to novel cosmetic compositionswhich contain the mixture of the invention.

According to a preferred embodiment of the invention, the mixture of theinvention is incorporated in said cosmetic composition at aconcentration of 0.2 to 90%, preferably 0.4 to 70%, more preferably 0.4to 5% and more preferentially 1 to 3%, by weight with respect to thetotal weight of said composition, of a mixture.

According to a variant of the invention, said composition ischaracterised in that it further contains at least one biologicallyactive agent such as a moisturising agent, an anti-wrinkle agent, ananti-oxidising agent, an anti-radical agent, an agent which repairs thedestructive effects of ultra violet rays or a slimming agent such ascaffeine.

According to a preferred embodiment of this variant of the invention,said composition is characterised in that it further contains a perfume,a cosmetically acceptable colouring material and/pr an agent whichprotects against UVA and UVB ultra violet rays, notably a filter or anano pigment, such as a zinc oxide or a titanium oxide.

According to various particular embodiments, said cosmetic compositionis characterised in that it can be presented in the form of a gel; alotion, a serum, a suspension, an emulsion, oil-in-water orwater-in-oil, or in solid form, e.g. in the form of a stick or a patch,or in dry form, e.g. in the form of a powder.

In order to prepare a dry form in the form of a powder, it will bepossible for example to vaporise, in a mixer, the mixture according tothe invention, dissolved beforehand in an aqueous excipient, onto aclassical cosmetic powder. Of course, the amount of mixture solutionvaporised will be compatible with the necessity of the upkeep of thepowder form. In general, this amount will not exceed 5%. According toanother method of incorporation of the mixture according to theinvention in a dry form, it will be possible for it to be fixed onto theexcipient, powder, such as talc, e.g. by means of a fluidised air bed.

The composition according to the invention forms a film which haselastomer-type mechanical properties with a texture which lends itselfparticularly well to make-up, and notably to the use of powders whichfix to it particularly well. Moreover, this type of texture possessesanti-migratory properties which can prove to be useful from anaesthetical point of view as well as from the point of view of comfortof use, notably in the proximity of sensitive zones, such as the eyesfor example.

According to a third aspect, the present invention relates to anothermethod of cosmetic care, characterised in that it comprises applyingtopically, on the zones of the skin concerned, an effective amount of acosmetic composition, as defined above, to obtain a smoothing effect onthe surface of the skin.

Advantageously, this method is also characterised in that, further tothe application of the cosmetic composition as defined above, and incase of reduction of the tightening effect on the surface of the skin, amoisturisation is carried out of the zones of the skin concerned havingreceived at least one first application of said cosmetic composition, soas to restore said tightening effect, notably by spraying water or acosmetically acceptable aqueous preparation.

By virtue of the mechanical effect of the tightening effect of themixture, as defined above, which is incorporated in a cosmeticcomposition, a partial or total erasure of wrinkles is obtained, andparticularly of medium and deep wrinkles. Stated otherwise, a smoothingof the surface of the skin is made which is visible, progressive anddurable. Said cosmetic composition also enables numerous imperfectionswhich are present on the surface of the skin to be remedied. Saidcosmetic composition does in fact have a non-negligible action upon thereduction of the visibility of certain imperfections which are commonlycalled <<orange peel>> imperfections, stretch marks, certain scars, aswell as certain zones of the skin which usually have folds, such as theneck for example.

The invention has another advantage in comparison with prior artcompositions having a tightening effect. As to the difference of theselatter compositions, the composition according to the invention has aprogressive tightening effect, and this in practice manifests itself byan absence of an effect called <<peak>> effect. The peak effect, forprior art compositions having a tightening effect, leads to a pulling ofthe skin and even, if necessary, to the rupture and/or to the detachmentof the polymer matrix. This peak effect can thus give rise to a brutaland sudden loss of the tightening effect on the surface of the skin.

It will be further noted that the good qualities presented by thecomposition according to the invention, as to the resistance to creepand to the loosening of the polymer matrix already mentioned, notablyenable higher amounts of actives, of fillers or of preservatives forexample, to be used.

Furthermore, the mixture according to the invention enables thepenetration of the actives to be increased in the skin, and the effectof this is to improve their bioavailability.

Thus, the invention also relates to the use of the mixtures according tothe invention as a cosmetic agent for promoting the penetration in theskin of a biologically active agent.

Thus, the mixture according to the invention enables the amount ofbiologically active agents penetrating in the skin to be increased withrespect to a given amount of these agents applied on the surface. Theeffect of this is to improve their bioavailability, stated otherwise, toincrease the amount available of these actives in the lower layers ofthe skin, and thus to contribute to increasing their effectiveness.

More specifically, the mixture according to the invention, particularlywhen it has been introduced in the formula of a cosmetic compositioncontaining a biologically active agent, firstly enables an accumulationof said biologically active agent to be obtained in the stratum corneum,commonly called the <<reservoir effect>>, and, secondly, a progressiveand prolonged release of this active towards the deepest layers of theskin. In comparison, a cosmetic composition, which would be identicalexcept that it would not contain the mixture according to the invention,would not present this reservoir effect and therefore would not enablethe penetration of such a large amount of active in the skin.

Thus, by virtue of the implementation of the present invention, it isnotably possible to obtain a double effect: to make a tightening effectof the skin, while at the same time obtaining an improved biologicaltreatment, in particular for biologically reducing or retarding theappearance of wrinkles, for improving or restoring the moisturisation ofthe skin, for reducing skin pigment marks, or even for obtaining aslimming effect.

Other aims, features and advantages of the invention will appear clearlyfrom the following description which is given from illustrative andnon-limiting examples of the invention which represent actuallypreferred embodiments. In the Examples, all percentages are given byweight, the temperature is ambient temperature, the temperature is givenin degrees Celsius and the pressure is atmospheric pressure, unlessindicated otherwise.

Example 15 is illustrated by FIGS. 1 and 2, which represent,respectively:

FIG. 1: the kinetics of caffeine penetration,

FIG. 2: the distribution of caffeine within skin beds after 14 hours and44 hours of contact.

EXAMPLE 1 Preparation of an Extract of the Alga Laminaria flexicaulis,which is Rich in Alginate in Gel Form

200 g of Laminaria flexicaulis alga is used here. Either the entire algaor a part of it, particularly the thalli, can be used.

The algae are first of all rinsed for 1 to 3 hours in cold water inorder to remove soluble substances, such as iodides. After having beenwashed, the algae are dried and then shredded before being bleached. Forthis, a classical bleaching method is used which consists of using 0.1%bleach and/or 3% hydrogen peroxide. The algae are immersed for avariable duration of 3 to 7 days in baths of bleach and/or baths ofhydrogen peroxide. At this stage of preparation, the product is rinsedabundantly with cold water and then finely ground in distilled waterwith the aid of a Turrax-type turbine at high speed, until a fluid gelis obtained. For this grinding, the proportion of dry product in wateris between 1 and 5 liters of water per 200 g of Laminaria flexicaulisalgae. The extract thus obtained, which is in the form of paste or gel,is colourless or very slightly beige and translucent. It is constitutedessentially of alginate and cellulose.

This extract is then advantageously dried according to procedures whichare well-known to the person skilled in the art. The dry alga extractthus obtained is ready to be incorporated for the preparation of aproduct having a tightening effect according to the invention.

EXAMPLE 2 Preparation of an Extract of Sorbs Rich in Sorbitol

Firstly, 50 g of whole sorbs originating from Sorbus aucuparia areground, and 50 ml of distilled water are then added, which is boiled for10 minutes so as to obtain a reduction of about 60 ml. Filtration isthen carried out under pressure (1 to 10 kg/cm²) through a sterile gauze(2 à5 strata, preferably 3) or a glass sieve (100 to 200 μm) inoxsinter. A pink coloured juice is thus obtained which can be used assuch, or indeed concentrated according to the means of use sought after.

The extract of sorbs thus obtained is ready to be incorporated for thepreparation of a product having a tightening effect according to theinvention.

Various examples of formulations of products will be given below, whichnotably have a tightening effect on the surface of the skin, and whichconstitute a basic product for the preparation of a cosmetic compositionaccording to the invention.

EXAMPLE 3 Mixture According to the Invention having a Very StiffTightening Effect

Na alginate 43.00% CMC  6.75% Concentrate according to Example 2 having70% of sorbitol 47.00% PVA    3% Cellulose  0.25%

EXAMPLE 4 Mixture According to the Invention having a Medium TighteningEffect

Dry extract of alga according to Example 1 50% (Extract having 85% ofalginate and 5% of cellulose) Concentrate according to Example 2 having70% of sorbitol 46% PVA 4%

EXAMPLE 5 Mixture According to the Invention having a Supple TighteningEffect

Na alginate 22% CMC 4% Concentrate according to Example 2 having 70% ofsorbitol 65% PVA 9%

EXAMPLE 6 Mixture According to the Invention having a Tightening EffectContaining PVP

Na alginate 42% CMC 4% Mannitol 49% PVP 5%

EXAMPLE 7 Mixture having a Tightening Effect According to the Invention

Sorbitol 64.68%  Alginate   22% PVA 9.15% CMC 4.17%

EXAMPLE 8 Tightening Mixture According to the Invention

Sorbitol 40% Sodium alginate 50% PVA 6% CMC 4%

EXAMPLE 9 Tightening Mixture According to the Invention

Sorbitol 46.05% Sodium alginate 46.05% PVA  3.8% CMC  4.1%

EXAMPLE 10 Tightening Mixture According to the Invention

Sorbitol 47% Alginate 43% PVA 3% CMC 7%

EXAMPLE 11 Cosmetic Composition Using the Product having a TighteningEffect on the Surface of the Skin According to the Invention Based onSodium Alginate and Sorbitol

Mixture according to Example 5   8% CMC 0.33%  Phenoxyethanol andparaben 0.5% Methyl parahydroxybenzoate 0.1% Purified water qs 100

EXAMPLE 12 Cosmetic Composition According to the Invention in Gel Form

Mixture, having a tightening effect of Example 7 2.8% Gellified aqueousexcipient+preservative+perfume qs 100

EXAMPLE 13 Anti-wrinkles Cosmetic Composition having a Tightening EffectAccording to the Invention, in Emulsion Form

This emulsion is constituted of:

Mixture, having a tightening effect of Example 7 0.8% Extract oftormentilla 0.5% Fatty phase  19% Gellified aqueous phase +preservative + perfume qs 100

This composition procures an immediate and prolonged tightening effect,and this enables a smoothing of the skin by a mechanical effect.Moreover, by virtue of the active plant extract for reducing wrinkles,this composition simultaneously, enables an even more durable reducingof wrinkles through a biological effect.

This biological effect is further reinforced by the <<reservoir effect>>which is procured by the presence in the composition of the mixtureaccording to the invention.

EXAMPLE 14 Evaluation of the Immediate Smoothing Effect on Wrinkles, invivo

1. Method:

An analysis of prints of wrinkles of the skin is made by a methodwithout contact with fringe projections.

This method is commonly used in various industries, notably formeasuring the roughness of a surface. This technique is for exampledescribed in the publication entitled <<Optical roughness measurementswith fringe projections> by Robert Windecker, Stefan Franz, Hans J.Tiziani, Applied optics, 1999, vol. 38, no 13, pp. 2837-2842.

Interference fringes are projected directly onto the skin with the aidof a specific optic and are captured as an image by a digital camera. Aphase image is calculated from fringe projection images and the altitudeof each point is determined.

Acquisition software enables 2D and 3D measurements of the skin to beobtained and enables the roughness parameters on a profile, the depthand the volume of the wrinkles, to be determined.

2. Protocol:

A zone on a wrinkle at the side of the eye of a volunteer, who had notapplied any product on the face since the evening before, is determinedand marked off. An image acquisition is then made.

A dose of 2 μL per cm² of composition according to the invention isapplied on this same zone.

A new image of this same zone is then acquired after 45 minutes and 4hours.

An automatic repositioning enables the specific re-identification of thezone of measurement at each time.

The images are compared with each other and three particular parametersare studied: the mean roughness Ra, the minimum deviation between thehighest peak and the deepest valley, Rt, and the mean value of themaxima, Rz.

The mean roughness Ra is defined as the ratio of the surface integratedaround the mean value, to the length of skin swept over.

3. Results:

The composition according to Example 13 of the invention applied ontothe skin reduces the mean roughness, Ra, of it by 13% after 45 minutesfrom application and by 21% after 4 hours from application.

The same tests show a lowering of the minimum deviation between thehighest peak and the deepest trough, Rt, by 18% after 45 minutes fromapplication and by 14% after 4 hours from application. In the same way,the mean value of the various maxima, Rz, decreases by 14% after 45minutes from application and by 19% after 4 hours from application.

These results show an immediate smoothing effect on the wrinkles, byvirtue of the application of the tightening composition according to theinvention.

EXAMPLE 15 Influence of the Mixture According to the Invention Upon theKinetics of Penetration of Caffeine

1. Aim of the Study

This study is made, in vitro, on human skin, which is kept beforehand byfreezing, with the aim of evaluating the influence of the mixtureaccording to the invention on the penetration and the distribution ofcaffeine within the skin beds. The occlusive properties of a gelaccording to the invention lead the research of an eventual patcheffect. This study is made in comparison with a Carbopol gel.

2. Methodology

The principle of the study is based on the evaluation of the diffusionof an active principle through the thawed human skin which is mounted onFranz cells.

These cells are constituted of two glass elements which delimit an upperpartition and a lower partition, and they have an exposed surface areaof 3.8 cm. The skin is placed between these two elements, stratumcorneum to the top. The active principle deposited on the skin crossesit and is collected in the lower partition, dissolved in a solutionwhich is known as the receptor solution and which is constituted of aphosphate buffer+Na nitride (0.1%) mixture.

The method refers to the COLIPA directives established in the field ofin vitro skin absorption moderation (c.f. Validation of the pig ear skinmodel for in vitro percutaneous absorption: inter-laboratoryreproducibility studies. CM. Vincent et al., Perspectives inPercutaneous Penetration, Vol. 7A, 2000).

1 mL of formulation, i.e. 5 mg of active principle (infinite dose), aredeposited at random on each explant. The study is made under anon-occlusive condition, so as to promote drying of the polymer and tothus enable an eventual patch effect. The experiments are repeated atthe rate of 6 Franz cells per product.

The formulations tested are the following:

Gel according to the Starting materials in % Control gel inventionCaffeine 0.5 0.5 Stachyose 1.0 1.0 Mixture of Example 7 — 1.2 Ethanol15.0 15.0 Carbopol 940 0.5 0.5 Triethanolamine 0.5 0.5 Phenoxetol 0.20.2 water 82.3 81.1a) Penetration Kinetics:

The penetration kinetics are established by samples of the survivalliquid between 8 and 40 hours from application.

b) Partitioning:

After 14 hours and 44 hours of contact, half of the cells are demountedand the biopsies undergo a washing treatment during which the excessemulsion on the skin surface is washed with the aid of a <<cotton woolbud>>. The cotton wool buds, as well as the upper part of the cell areimmersed in 10 ml of 50/50 methanol/water mixture for 30 minutes withagitation. The solution is then filtered and diluted to a 1/10th in amethanol/water solution (50/50) before determination.

The stratum corneum is collected by 8 successive exfoliations by meansof an adhesive strip, by applying a pressure of 300 g/cm² for 12seconds. The caffeine is extracted by dissolving in 2 mL ofmethanol/water under stirring for 30 minutes.

The epidermis is separated from the dermis by heating at 60° C. for 12seconds, and is then separated from the dermis with the aid of a finepincer. The caffeine is extracted by contact with 2 ml of methanol/waterover 24 hours.

The dermis is placed in 2 mL of methanol/water, for 24 h.

The epidermal and dermal suspensions are agitated for 2 hours and arefiltered at 0.45 μm before determination.

The determination of caffeine is made by HPLC.

3. Expression of the Results

The amount of active principle collected within the various biologicalpartitions studied is expressed in μg/mL.

The kinetics of penetration, in μg/cm² per unit time, is expressed as afunction of the interval of confidence, the IC_(95%), wherein theresidual standard deviation is calculated by the ANOVA method over thewhole of the tests.

The partitioning is the percentage of caffeine absorbed as a function oftime: for each partition studied, the proportion of caffeine absorbed iscalculated from the amounts collected with respect to the amountsapplied.

4. Results

a) Caffeine Solubility Limit:

In order to prevent any risk of under-estimation of the skin absorption,the concentration of active principle in the receptor liquid must beless than 10% of the solubility limit concentration (Guidelines forpercutaneous absorption, Colipa, November 95).

At 37° C., the caffeine solubility limit concentration in the receptorliquid is 16 mg/mL. The maximum concentration of caffeine collectedduring the study is less than 23 μg/mL; the experimental conditions aretherefore correct.

b) Caffeine Penetration Kinetics, in vitro:

FIG. 1 indicates the amounts of caffeine collected in the receptorliquid as a function of time.

The kinetics of penetration of caffeine, from the formulation containingthe composition according to the invention, is higher than with thecontrol gel based on Carbopol. At 40 hours, the caffeine concentration(33.6 μg/cm²) which is present in the receptor liquid, after applicationof the gel according to the invention, is greater than that determinedafter application of the control gel (24.0 μg/cm²).

In drying, the gellifying complex according to the invention causes aslight occlusive effect which promotes the percutaneous absorption ofthe active principle.

An analysis of variance (ANOVA), which is completed by a Newman-Keulsclassification test, was made in order to verify whether a significantdifference exists between the amounts absorbed after 12 hours, 40 hoursand all times together.

The statistical study made shows that under the experimental conditions,the addition of the mixture according to the invention in a gelsignificantly promotes the penetration of caffeine in the skin covering.

5. Partition Study:

The proportion of caffeine absorbed is calculated from the amountscollected with respect to the amounts applied.

The distribution of caffeine within the skin beds after 14 and 44 hoursof contact is given in the Table below, wherein the results areexpressed in %.

After 14 hours After 44 hours Gel of the Gel of the invention Controlgel invention Control gel STRATUM 0.65 0.31 0.10 0.26 CORNEUM EPIDERMIS0.10 0.11 0.04 0.04 DERMIS 0.56 0.62 0.30 0.32 RECEPTOR 1.41 1.42 2.192.00 LIQUID

The analysis of the results given in the Table above and in FIG. 2 showsa better accumulation of caffeine after 14 hours in the horny layerafter application of the gel according to the invention, thus giving animprovement of the reservoir effect of the stratum corneum. Thisobservation is representative of a patch effect.

6. Conclusions

The patch effect of the gel according to the invention manifests itselfexperimentally by:

-   -   A tendency to improve the reservoir effect of the stratum        corneum vis-à-vis caffeine, in thus promoting its        bioavailability.    -   Kinetics of caffeine penetration which are significantly higher        after addition of the gel according to the invention.

The invention claimed is:
 1. A mixture, having a skin-tightening effect,consisting essentially of 20 to 55% by weight of a polysaccharide havinga molecular weight of less than 600,000 Daltons selected from the groupconsisting of a pectin, a carrageenan, a galactomanane, a xanthan andalginate, 40 to 75% by weight of a polyhydroxylated agent selected fromthe group consisting of glucose, sorbitol, mannitol, and galactitol, 3to 15% by weight of poly(vinyl alcohol) or polyvinylpyrrolidone, and 1to 8% by weight of a cellulose component selected from cellulosecarboxymethylcellulose and hydroxymethylcellulose.
 2. The mixtureaccording to claim 1, wherein said polysaccharide is an alginate, analginate of propylene glycol, an alginate in the form of an acid, analginate in the form of a salt, or a sodium alginate.
 3. The mixtureaccording to claim 2, wherein said alginate is in the form of an extractof alga.
 4. The mixture of claim 1, wherein said sugar is mannitol. 5.The mixture according to claim 1, wherein said sugar is sorbitol.
 6. Themixture according to claim 5, wherein the sorbitol is in the form of aplant extract.
 7. The mixture according to claim 1, wherein saidhydroxylated agent is at a concentration of between 40 and 65% byweight.
 8. The mixture according to claim 1, wherein said mixturecontains a Laminaria flexicaulis extract and an extract of sorbs.
 9. Themixture according to claim 1, wherein the concentration ofpolysaccharide is greater than the concentration of polyhydroxylatedagent.
 10. The mixture according to claim 1 wherein the concentration ofpolyhydroxylated agent is greater than the concentration ofpolysaccharide.
 11. The mixture according to claim 1, wherein saidmixture contains 3 to 10% by weight of poly(vinyl alcohol) orpolyvinylpyrrolidone.
 12. The mixture according to claim 1, consistingessentially of 20 to 55% by weight of alginate, 40 to 75% by weight ofsorbitol or mannitol, 3 to 15% by weight of poly(vinyl alcohol) orpolyvinylpyrrolidone, and 1 to 8% by weight of carboxymethylcellulose.13. A cosmetic composition comprising the mixture of claim 1 in anamount of 0.2 to 90% by weight with respect to the total weight of saidcosmetic composition and further comprising at least one cosmeticallyactive agent, selected from a moisturizing agent, an anti-wrinkle agent,an anti-oxidizing agent, an antiradical agent, an agent which repairsthe destructive effects of ultra violet rays, or a slimming agent. 14.The cosmetic composition according to claim 13, wherein said slimmingagent comprises caffeine.
 15. The cosmetic composition according toclaim 13, further comprising at least one selected from a perfume, acosmetically acceptable colouring material, an agent which protectsagainst UVA or UVB ultra violet rays, a filter or a nano pigment, a zincoxide or a titanium oxide.
 16. The cosmetic composition according, claim13, wherein said cosmetic composition is in the form of a gel, a lotion,a serum, a suspension, an oil-in-water emulsion, water-in-oil emulsion,in solid form, in stick form, in patch form, in dry form, or in powderform.
 17. A method of cosmetic care, comprising applying topically, onthe zones of the skin concerned, an effective amount of the cosmeticcomposition, as defined in claim 13, to obtain a smoothing effect on thesurface of the skin.
 18. The method according to claim 17, wherein afterat least one application of said cosmetic composition on the surface ofthe skin, a moisturisation is carried out on said surface of the skin,and said surface of the skin is further sprayed with water or a cosmeticaqueous preparation and wherein said tightening effect is restored orincreased.
 19. The mixture according to claim 1, wherein saidpolysaccharide has a molecular weight of less than 400,000 Daltons. 20.The mixture according to claim 1, wherein said polysaccharide has amolecular weight of less than 200,000 Daltons.
 21. The mixture accordingto claim 3, wherein said extract of alga is an extract of alga of thefamily Laminariacae.
 22. The mixture according to claim 21, wherein saidextract of alga of the family Laminariacae is selected from Laminariadigitata alga, Laminaria flexicaulis alga, and Laminaria saccharinaalga.
 23. The mixture according to claim 6, wherein said extract is anextract of sorbs.
 24. The mixture according to claim 23, wherein saidextract of sorbs is selected from Sorbus aucuparia sorb extract, Sorbusdomestica sorb extract, and Sorbus aria sorb extract.
 25. The mixtureaccording to claim 8, wherein said extract of sorbs is an extract ofSorbus aucuparia sorbs.
 26. The mixture according to claim 12, whereinthe weight of said sorbitol or mannitol is 40 to 65%.
 27. The mixtureaccording to claim 12 wherein the weight of said poly(vinyl alcohol) orpolyvinylpyrrolidone is 3 to 10%.
 28. The cosmetic composition accordingto claim 13, wherein said mixture is present in an amount between 0.4 to70% by weight with respect to the total weight of said cosmeticcomposition.
 29. The cosmetic composition according to claim 13 whereinsaid mixture is present in an amount between 0.4 to 5% by weight withrespect to the total weight of said cosmetic composition.
 30. Thecosmetic composition according to claim 13, wherein said mixture ispresent in an amount between 1 to 3% by weight with respect to the totalweight of said cosmetic composition.
 31. A method of cosmetic care forpromoting the penetration in the skin of a biologically active agent,comprising applying topically on the zones of the skin concerned, aneffective amount of mixture as defined in claim 1, to obtain saidpromotion of said penetration of said active agent.
 32. A cosmeticcomposition having a skin-tightening effect, in a form selected from agel, a lotion, a suspension, an oil-in-water emulsion, a water-in-oilemulsion, a solid form, a stick form, a patch form, a dry form, or apowder form, said composition comprising a mixture consistingessentially of 20 to 55% by weight of a polysaccharide having amolecular weight of less than 600,000 Daltons selected from the groupconsisting of a pectin, a carrageenan, a galactomanane, a xanthan andalginate, 40 to 75% by weight of a polyhydroxylated agent selected fromthe group consisting of glucose, sorbitol, mannitol, and galactitol, 3to 15% by weight of poly(vinyl alcohol) or polyvinylpyrrolidone, and 1to 8% by weight of a cellulose component selected from cellulosecarboxymethylcellulose and hydroxymethylcellulose.
 33. The compositionaccording to claim 32, wherein said composition comprises said mixturein an amount ranging between 0.2 and 90% by weight of the total weightof said cosmetic composition.
 34. An anti-wrinkle cosmetic compositionin emulsion form having a tightening effect constituted of: 0.8 weight %of a mixture having a tightening effect comprising 64.68 weight % ofsorbitol, 22 weight % of alginate, 9.15 weight % of polyvinyl alcoholand 4.17 weight % of carboxymethylcellulose; 0.5 weight % of an extractof tormentilla; 19 weight % of fatty phase; and Qs 100 weight % of agellified aqueous phase.